Hi everyone

I encountered Agoh's Conjecture:

$\displaystyle

nB_{n-1}\equiv-1\quad mod \quad n

$

When n is prime.

Bn is the n th Bernoulli numer.

How can we extract modulo from fractions?

I red somewhere about minimal residue but i did not understand exacty what it is.

Can you give me some examples (modulo of fractions)?

Thank you for your time